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6.40. RASSCF
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etc., producing a file with extension ’.GvOrb’. When this is used as INPORB file, the selected
orbitals will be picked in the correct order.
An INPORB file with typeindex can also be used to provide orbital specs while the CMO data
are taken from another source (JOBOLD, RUNFILE, . . . ). This is achieved by TYPEINDEX,
and you can look in the manual for this keyword to see an explanation of how the typeindex
is written. (This is usually done by the program generating the file, but since these are
ASCII files, you may find it expedient to look at, or edit, the typeindex).
In case both keywords, such as INACTIVE, and LUMORB, is given, this is of course the
very common case that CMO data are read from INPORB but orbital specs are given by input.
This is perhaps the most common usage. However, when the INPORB file is a produced by GV,
it happens frequently that also keyword specs are left in the input, since the user knows that
these merely duplicate the specs in INPORB. But the latter may also imply a reordering of the
orbitals. For this reason, when the keyword input merely duplicates the number of inactive,
etc., that is also specified by typeindex, then the typeindex input overrides, to produce the
correct ordering. If they do not match precisely, then the CMO data are read, without
reordering, and the keyword input (as usual) takes precedence.
The CMO data are obtained as follows: With the following keywords, it is assumed that the
user knows what he wants.
• CORE: (A bad choice, but here for completeness). Creates orbitals from scratch.
• LUMORB or FILEORB: Try INPORB, or fail.
• JOBIPH: Try JOBOLD, if not usable, try JOBIPH, or fail.
If none of these keywords were used, then the user accepts defaults, namely
1. look for RASSCF orbitals on RUNFILE
2. look for SCF orbitals on RUNFILE
3. look for GUESSORB orbitals on RUNFILE
4. If still nothing found, create orbitals from scratch.
As for earlier versions, notice the possibility to read the orbitals on JOBIPH, at a later
time, by using the keywords OUTOrbital and ORBOnly. This results in editable ASCII
files, with names like Project.RasOrb (or Project.RasOrb5 for the fifth root). Such orbitals will be produced by default for the lowest roots – up to the tenth, named now, e.g.,
Project.RasOrb.5. There is a keyword MAXORB to produce more (or fewer) such files.
The RASSCF program has special input options, which will limit the degrees of freedoms
used in the orbital rotations. It is, for example, possible to impose averaging of the orbital
densities in π symmetries for linear molecules. Use the keyword Average for this purpose.
It is also possible to prevent specific orbitals from rotating with each other. The keyword is
Supsym. This can be used, for example, when the molecule has higher symmetry than one
can use with the Molcas system. For example, in a linear molecule the point group to be
used is C2v or D2h . Both σ− and δ−orbitals will then appear in irrep 1. If the input orbitals
have been prepared to be adapted to linear symmetry, the Supsym input can be used to
keep this symmetry through the iterations. The program will do this automatically with the
use of the input keyword LINEAR. Similarly, for single atoms, spherical symmetry can be
enforced by the keyword ATOM.